Nonlinear evolution causes the galaxy power spectrum to become broadly correlated over different wavenumbers. It is shown that prewhitening the power spectrum – transforming the power spectrum in such a way that the noise covariance becomes proportional to the unit matrix – greatly narrows the covariance of power. The eigenfunctions of the covariance of the prewhitened nonlinear power spectrum ...

This work introduces direction of arrival (DOA) estimation considering the sparsity prior in low signal to noise ratio (SNR) using deep learning (DL). The representation can be prompted realize super-resolution DOA spatial spectrum. undersampled noisy linear measurements spectrum, which is formulated by columns array covariance matrix, given as input neural network for estimation.The convolutio...

The paper presents a methodology for calculating the flight dynamic characteristics and gust response of highly flexible aircraft. The aeroelastic model is based on a geometricallyexact, nonlinear beam model coupled with large angle aerodynamic model. The gust response is calculated based on various gust models. It is shown that the calculated gust response spectrum as well as the RMS values ca...

Nonlinear bistable systems have been shown to provide improved efficiency for harvesting energy from random and broadband vibration sources. This article explores the distinct frequency response in the broadened spectrum of a particular nonlinear energy harvester, a piezoelectric cantilever with magnetic coupling. The cantilever response evolves dynamically with frequency around the main cantil...

For seismic resistant design of critical structures, a dynamic analysis, based on either response spectrum or time history is frequently required. Due to the lack of recorded data and randomness of earthquake ground motion that might be experienced by the structure under probable future earthquakes, it is usually difficult to obtain recorded data which fit the necessary parameters (e.g. soil ty...

This paper studies the nonlinear vibration analysis of a simply supported Euler-Bernoulli beam resting on a nonlinear elastic foundation under compressive axial load using nonlinear normal modes concept in the case of three-to-one (3:1) internal resonance. The beam’s governing nonlinear PDE of motion and also its boundary conditions are derived and then solved using the method of Multiple Time ...

We show that graphene possesses a strong nonlinear optical response in the form of multiplasmon absorption, with exciting implications in classical and quantum nonlinear optics. Specifically, we predict that graphene nanoribbons can be used as saturable absorbers with low saturation intensity in the far-infrared and terahertz spectrum. Moreover, we predict that two-plasmon absorption and extrem...

Few experimental and complementary theoretical studies have investigated high-frequency (>20 MHz) nonlinear responses from polymer-shelled ultrasound contrast agents. Three polymer agents with different shell properties were examined for their single-bubble backscatter when excited with a 40 MHz tone burst. Higher-order harmonic responses were observed for the three agents; however, their occur...

The Eulerian cosmological fluid equations are used to study the nonlinear mode coupling of density fluctuations. We evaluate the second-order power spectrum including all four-point contributions. In the weakly nonlinear regime we find that the dominant nonlinear contribution for realistic cosmological spectra is made by the coupling of long-wave modes and is well estimated by second order pert...

An organic nonlinear optical single crystal of gamma glycine (GGLY) has been grown by slow evaporation of the saturated solution at room temperature. Single crystal of gamma glycine (GGLY), an organic nonlinear optical (NLO) material, has been grown by slow solvent evaporation technique. Good optical quality single crystals with dimension up to 31 × 30 × 6 mm are obtained. The crystals are char...